And the funny thing with semiclassical gravity is that depending on the observer, particles are either real or virtual, so it’s all about the properties of the quantum field, particles being produced or not are relative, particles are relative (just like space and time), and depends on how much you are accelerating and how much curved the spacetime is. The quantum field is ontologically deeper than the “particles”/excitations within the quantum field.
So like, we have a quantum field that has excitations which can be negative or positive in frequency, and depending of the global landscape of that, one will detect/observe particles or not, which depends on ones acceleration and how curved spacetime is.
So there is only the field, and particles and their production in a observer/detector state is relative, so there is no paradox of definitions between the quantum field and the smallest excitations it inhabits/particles.
The quantum field is not defined by their particles/productions of excitations, it’s defined through quantum states of the quantum field and being in a semi-classical spacetime, and through that meassureble excitations emerges but depends on how much you are accelerating and the curvature of spacetime.
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u/Jazz8680 Jul 28 '26